Eiichi Makino

S100C/A11 is a key mediator of Ca2+-induced growth inhibition of human epidermal keratinocytes

An increase in extracellular Ca2+ induces growth arrest and differentiation of human keratinocytes in culture. We examined possible involvement of S100C/A11 in this growth regulation. On exposure of the cells to high Ca2+, S100C/A11 was specifically phosphorylated at 10Thr and 94Ser. Phosphorylation facilitated the binding of S100C/A11 to nucleolin, resulting in nuclear translocation of S100C/A11. In nuclei, S100C/A11 liberated Sp1/3 from nucleolin. The resulting free Sp1/3 transcriptionally activated p21CIP1/WAF1, a representative negative regulator of cell growth. Introduction of anti-S100C/A11 antibody into the cells largely abolished the growth inhibition induced by Ca2+ and the induction of p21CIP1/WAF1. In the human epidermis, S100C/A11 was detected in nuclei of differentiating cells in the suprabasal layers, but not in nuclei of proliferating cells in the basal layer. These results indicate that S100C/A11 is a key mediator of the Ca2+-induced growth inhibition of human keratinocytes in culture, and that it may be possibly involved in the growth regulation in vivo as well.

Introduction of an N-terminal peptide of S100C/A11 into human cells induces apoptotic cell death

S100 proteins belong to the EF-hand Ca2+-binding protein family and are involved in the regulation of a variety of cellular processes. Individual S100 proteins are expressed in cell- and tissue-specific manners, and functional deterioration of S100 proteins leads to a number of human diseases, including cancer. We previously demonstrated that S100C/A11 was translocated to nuclei and inhibited DNA synthesis in human keratinocytes when exposed to high Ca2+. In the present study we examined the effects of synthetic partial peptides of S100C/A11 on human carcinoma cell lines. Only an N-terminal peptide with 19 amino acid residues (MAK19) showed cytotoxicity to the cell lines in dose- and time-dependent manners when introduced into cells by flanking the HIV-TAT protein transduction domain (TAT-MAK19). Pulse field electrophoresis revealed that DNA of the treated cells was partially degradated. Annexin V, a marker of cellular apoptosis, was detected in the cells treated with TAT-MAK19 by immunostaining and flow cytometry. The induction of apoptotic cell death was apparently independent of p53, p21WAF1/CIP1, and caspase activity, but treatment with TAT-MAK19 resulted in partial translocation of apoptosis-inducing factor (AIF) from the cytoplasm to nuclei. These results indicate that MAK19 induces apoptosis in human cell lines and may therefore lead to the establishment of a new molecular target for the treatment of human cancer.

Minimal Change Nephrotic Syndrome Developing during Postoperative Interferon-Beta Therapy for Malignant Melanoma

A 64-year-old man presented with proteinuria during postoperative interferon (IFN)-β therapy against malignant melanoma. Renal pathologic findings were consistent with minimal change nephrotic syndrome (MCNS) showing extensive foot process effacement of visceral glomerular epithelial cells (podocyte). Nephrotic range proteinuria gradually regressed after stoppage of local injection of IFN-β without glucocorticoid treatment. To our knowledge this is the first report that demonstrates histological abnormalities of the glomerulus associated with postoperative IFN-β therapy for the malignant melanoma.

Neutrophilic Eccrine Hidradenitis: Report of Two Cases

Neutrophilic eccrine hidradenitis (NEH) is an uncommon, self‐limited dermatosis usually attributed to anti‐cancer chemotherapy. It is characterized histologically by necrosis of the eccrine gland and neutrophilic infiltrate.

Successful treatment with infliximab for refractory pyoderma gangrenosum associated with inflammatory bowel disease

Dear Editor, Pyoderma gangrenosum (PG) is a rare, chronic, neutrophilic skin disease in which painful nodules or pustules break down to form progressively enlarging ulcers with raised, tender, undermined borders. The pathogenesis of PG remains unknown, and it occurs in approximately 36–50% of cases of inflammatory bowel disease (IBD). There is no gold standard for PG treatment yet, and treatment options depend on multiple factors including size and depth of the lesion, the presence of underlying disease and the general medical status of the patient. In this report, we present a patient with IBD-associated PG, who was resistant to conventional therapy over a period of 4 years. A 36-year-old Japanese man visited our department in May 2006 with painful ulcerative erythema on his left chest. He had indeterminate colitis, a subgroup of IBD, which cannot be classified as Crohn’s disease or ulcerative colitis. In 2006, he was treated with oral prednisolone (10 mg ⁄ day) and mesalazine (3 g ⁄ day). Histology of the ulcerative erythema showed a dense neutrophilic (a) (b)

The structure of S100A11 fragment explains a local structural change induced by phosphorylation.

S100A11 protein is a member of the S100 family containing two EF‐hand motifs. It undergoes phophorylation on residue T10 after cell stimulation such as an increase in Ca2+ concentration. Phosphorylated S100A11 can be recognized by its target protein, nucleolin. Although S100A11 is initially expressed in the cytoplasm, it is transported to the nucleus by the action of nucleolin. In the nucleus, S100A11 suppresses the growth of keratinocytes through p21CIP1/WAF1 activation and induces cell differentiation. Interestingly, the N‐terminal fragment of S100A11 has the same activity as the full‐length protein; i.e. it is phosphorylated in vivo and binds to nucleolin. In addition, this fragment leads to the arrest of cultured keratinocyte growth. We examined the solution structure of this fragment peptide and explored its structural properties before and after phosphorylation. In a trifluoroethanol solution, the peptide adopts the α‐helical structure just as the corresponding region of the full‐length S100A11. Phosphorylation induces a disruption of the N‐capping conformation of the α‐helix, and has a tendency to perturb its surrounding structure. Therefore, the phosphorylated threonine lies in the N‐terminal edge of the α‐helix. This local structural change can reasonably explain why the phosphorylation of a residue that is initially buried in the interior of protein allows it to be recognized by the binding partner. Copyright